I've been doing a lot of searching around for lenses for my ME Super, and have learned a lot about them, so I thought I'd write up this guide. A Word About Quality The best lenses you can buy for your Pentax 35mm are, not surprisingly, made by Pentax. There are a few other companies that make lenses for Pentax cameras (both k-mount and screw mount). Most notably: Tamron, Sigma, and Vivitar, though there are some eastern european companies that have made m42 screw-mount lenses that will fit on your camera. These lenses, however, are not nearly as good as the Pentax ones for the most part. The most common complaint is that they become very soft when you open the aperture too wide, or during zooms that enter the "telephoto" range (upwards of 135mm). Those are serious problems. After all, if you wanted a soft image, you could have bought a soft focus lens, or a softening filter. Some lenses are deceptively good-looking. For example, Sigma, Tamron, and Vivitar all make APO lenses for Pentax bodies (they're all autofocus except for the Vivitar), but these lenses still have the same softening, and sometimes vignetting problem. You might get a photo with fewer chromatic abberations, but you'll lose quality elsewhere. So stick with the Pentax brand. Though some Pentax lenses will soften when opened wide or fully zoomed in, in my experience the results will be much less noticeable than with a lens from a competing brand. I should add here that Tamron and Sigma have good reputations these days. Their newer glass is very good. Not quite so much with their actual k-mount lenses, which are older and of a different design. The adapt-all's are fine if you're willing to put up with the adapter. Avoid Vivitar zoom lenses like the plague. Coated or Non Coated/What do those acronyms mean? SMC stands for "super multi coated." As we all know, coated lenses are better than non-coated ones, and "multi-coated" even better. Most of the time, you aren't going to see any Pentax lenses that aren't SMC unless you're looking at older screw-mount ones. If you are looking at screw-mounts, you'll probably come across "Takumar" lenses. This was the name given to Pentax's first line of SLR lenses. Unless you're looking for a 37mm screw-mount lens for an old Asahiflex, you don't want a plain old Takumar. The Super Takumars featured an early type of lens coating, with the SMC Takumars following later, with more modern, multi-coated glass. Okay, so SMC Pentax it is. If you're shopping for a lens for a k-mount manual focus camera, try your best to stay away from anything with a "D," for digital, and anything autofocus. What about SMC-P, F, FA, A, M, etc? This system isn't necessarily as intuitive as it may seem. "A" does, indeed stand for auto, but not auto focus. Something like SMCP-A means that the lens has a selection on the aperture ring for automatic aperture, not automatic focus. The F and FA lenses are the autofocus ones. They will work on a manual focus body, but a manual focus lens is preferable. Stick to SMC-A, SMC-M, SMCP-A, or SMCP-M, if you can help it. Speed Racer The fastest lens that Pentax makes is the SMCP-A 50mm f1.2. That's pretty damn fast. It's also very expensive (in the neighborhood of $700 new. KEH has a couple used for around $300). At this point you should be asking yourself how fast you really need your lens to be. In the 50mm length, Pentax makes an f1.2, f1.4, f1.7, and an f.2. The SMCP-A 2.0 is the stock lens for most 35mm Pentax cameras. It is the easiest and cheapest to come by, and takes exceptional pictures. Older ones are easy to come by, and newer ones are dirt cheap (i.e. about $50-$75 brand new). The 1.7 is also very nice, gaining a bit of speed, and tends to sell on eBay and KEH for about the same price as the 2.0 The 1.4 is also quite good, though the older Takumar f1.4's may give you cancer or set off nearby geiger counters, as they used a radioactive lens element. If you're looking for something longer that can keep up with the speed of the 50mm line, don't hold your breath. While Pentax did make an 85mm f1.4 and a 135mm f1.8, they're rather rare, and pretty expensive.